JP2005073177A - Substrate for diode mounting, and millimeter wave module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for diode mounting which can reduce variation of diode characteristics of a mounted Schottky barrier diode. <P>SOLUTION: In the substrate for diode mounting, the diode which is used for a high frequency circuit block which uses a nonradioactive dielectric line is mounted on a surface. Relative permittivity is uniform in a plane of the inside of the substrate which plane is parallel to the surface. Distribution of relative permittivity in the plane of the inside of the substrate which plane is parallel to the surface is not present, and the diode mounted on the surface is not influenced by distribution of relative permittivity, so that the substrate for diode mounting which can stably show superior diode characteristic is realized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is for mounting a high-frequency diode such as a Schottky barrier diode used for a switch element or the like when a millimeter wave module such as an inter-vehicle radar or a high-speed communication is configured using a non-radiative dielectric line. The present invention relates to a diode mounting board and a millimeter wave module using the same, and more particularly to a diode mounting board with improved individual differences and a millimeter wave module using the same.

  In a millimeter-wave module such as a millimeter-wave high-speed modulator, a high-frequency diode such as a PIN diode, a Schottky barrier diode, or a varactor diode is used as a modulation element as a modulation unit for performing millimeter-wave modulation. These diodes are used by being mounted on a diode mounting substrate (for example, see Non-Patent Document 1).

Conventionally, a diode mounting board for mounting these high-frequency diodes is a board in which an insulating layer made of a resin is laminated in order to maintain the strength required for mounting the diode or using the diode mounted state. The substrate was formed by laminating a so-called glass epoxy resin insulating layer in which a glass cloth or the like impregnated with the resin was laminated.
Kuroki and two others, “NRD-guided high-speed ASK modulator using Schottky barrier diode”, 1997 IEICE General Conference Proceedings Electronics 1, March 24-27, 1997, p.120

  However, the substrate made of glass epoxy resin used for the conventional diode mounting substrate has a uniform dielectric constant in the plane because the insulating layer is made of resin between the glass cloth layers laminated inside. However, in the glass cloth layer, the dielectric constant differs between the glass cloth fiber and the resin, and the resin penetrates between the glass fibers to form an insulating layer. The relative permittivity is not uniform in a plane parallel to the substrate surface, which is a plane, and has a relative permittivity distribution.

  For this reason, in the conventional diode mounting substrate, the relative permittivity distribution does not appear as a large difference when viewed as the entire substrate, but the insulating layer has a relative dielectric constant in a plane parallel to the inner surface of the mounting substrate. When mounted on the surface, the characteristics of high-frequency diodes such as Schottky barrier diodes are affected by minute changes in the relative dielectric constant of the surroundings. There has been a problem that variations in diode characteristics appear as large. And the influence on the diode characteristics due to such a small distribution of relative permittivity is different for each diode mounting board because the position of the internal glass cloth is different for each board. There is a problem that it is difficult to stably obtain uniform diode characteristics.

  The present invention has been made in view of such problems in the prior art, and its purpose is to suppress the influence of the mounted diode from the substrate and stabilize the uniform diode characteristics after mounting. Another object is to provide a diode mounting substrate that can be obtained.

  Another object of the present invention is to provide a millimeter wave module that can stably obtain desired characteristics, including a diode mounting substrate that can stably obtain uniform diode characteristics for a mounted diode. Is to provide.

  The diode mounting substrate of the present invention is a diode mounting substrate used for a high frequency circuit block using a non-radiative dielectric line, on which a diode is mounted, and in a plane parallel to the surface inside the diode mounting substrate. The relative dielectric constant is uniform.

  The millimeter wave module of the present invention includes a non-radiative dielectric line, the diode mounting substrate of the present invention having the above-described configuration, and a diode mounted on the surface thereof.

  According to the diode mounting substrate of the present invention, the relative permittivity is uniform in a plane parallel to the surface on which the diode is mounted inside the substrate, and in the plane parallel to the surface on which the diode is mounted. Since there is no distribution of relative permittivity, it does not affect the characteristics of the high-frequency diode mounted on the surface by causing minute changes in the relative permittivity of the surroundings. The diode characteristics do not appear to vary greatly later, and the effect on the diode characteristics does not differ from one mounting board to another, and uniform diode characteristics after mounting can be stably obtained. be able to.

  In addition, according to the millimeter wave module of the present invention, since the diode mounting substrate of the present invention and the diode mounted on the surface thereof are provided, the diode mounted on the diode mounting substrate has uniform diode characteristics. Since it can be obtained stably, good diode characteristics as a modulation unit for performing millimeter wave modulation can be stably obtained as desired, and desired characteristics as a millimeter wave module can be obtained stably. be able to.

  The substrate for mounting a diode according to the present invention has no distribution of permittivity in a plane parallel to the surface on which the diode inside the substrate is mounted, and a glass cloth and resin like a conventional substrate made of glass epoxy resin. By not including those that cause the distribution of relative permittivity, such as the combination of and the like, modulation of millimeter waves is possible without affecting the mounted diodes. As the diode functioning as the unit, for example, the phase of the modulated millimeter wave can be made uniform, and desired characteristics can be stably obtained.

  Further, by using a high-frequency diode with a small individual difference in diode characteristics, variation in characteristics of the entire millimeter-wave circuit can be extremely reduced, and a high-performance millimeter-wave circuit can be configured.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a plan view showing an example of an embodiment of a diode mounting substrate of the present invention. In FIG. 1, reference numeral 1 is a substrate, and 2 is a diode mounting pad formed on a surface of the substrate 1 and on which high-frequency diodes are mounted. Reference numeral 3 denotes a high-frequency choke pattern connected to the diode mounting pad 2.

  In the diode mounting substrate of the present invention, the substrate 1 is a diode (not shown) mounted on the surface thereof using the diode mounting pad 2, and in a plane parallel to the inner surface thereof, It is important that the relative permittivity is uniform, not having a relative permittivity distribution unlike the glass cloth layer of a conventional glass epoxy resin substrate.

  The substrate 1, the diode mounting pad 2 and the choke pattern 3 are for mounting a diode for processing a high frequency signal, and the loss of the dielectric material forming the substrate 1 is small and used. The conductivity of the metal constituting the diode mounting pad 2 and the choke pattern 3 must be high. In addition, since the design dimension depends on the relative dielectric constant of the substrate 1, it is difficult to stably mass-produce unless the individual difference in dielectric constant is small. Furthermore, since the size of the mounted diode is usually 1 mm □ or less, the relative permittivity must be in-plane distribution within a range of several mm □ in the vicinity of the diode mounting pad 2. Specifically, a substrate 1 made of a low-loss dielectric material such as ceramics or single crystal is formed with a pattern to be a diode mounting pad 2 or choke pattern 3 using a low resistance material such as copper, silver or gold. Alternatively, a substrate 1 made of a low-loss resin material such as Teflon (R), polyimide, liquid crystal polymer, epoxy, or the like may be used, such as a diode mounting pad 2 or a choke pattern 3 made of copper.

  The pair of diode mounting pads 2 formed on the surface of the substrate 1 is obtained by forming a conductive pattern such as copper, silver or gold on the substrate 1 made of ceramics or single crystal using thick film printing or the like, or the substrate 1 A thin film made of copper, silver, gold or the like is formed and etched to form a pattern, or a thin film formed by etching a copper-clad substrate, or a conductive thin film on a substrate 1 made of resin. A pattern formed by etching or the like can be used.

  Further, the high frequency choke pattern 3 formed by being connected to each of the diode mounting pads 2 mainly conducts a direct current component for biasing the mounted diode, and leaks a millimeter wave component to the ground or the like. What is necessary is just to determine a dimension etc. combining the patch etc. of the magnitude | size determined according to the frequency to be used. The pattern may be formed at the same time as the diode mounting pad 2.

  A high-frequency diode such as a PIN diode, a Schottky barrier diode, or a varactor diode is mounted between the diode mounting pads 2 on the surface of the diode mounting substrate of the present invention having such a configuration. The diode mounting substrate on which the diode is mounted in this manner is used as a diode mount, for example, in a modulation section of a millimeter wave circuit. At this time, it is preferable to use a non-radiative dielectric line (NRD guide) for the millimeter wave input / output to / from the diode because it is a three-dimensional circuit that has a small millimeter wave transmission loss and is easy to design.

  Such a non-radiative dielectric line is a parallel-plate-like lower conductor at a predetermined interval of λ / 2 or less with respect to a wavelength λ of an electromagnetic wave (high frequency signal) propagating in the air at a use frequency. By interposing a dielectric line between the plate and the upper conductor plate, electromagnetic waves of high frequency signals can propagate along the dielectric line, and the radiated wave is suppressed by the blocking effect by the lower conductor plate and the upper conductor plate. It is configured based on the operating principle. In addition to being arranged in a straight line, the dielectric line may be arranged in a curved line, so that the electromagnetic wave of the high-frequency signal can be easily propagated in a curved line. This has the advantage that circuit design with a high degree of freedom can be achieved. In addition, the use frequency in which the nonradiative dielectric line combined with the diode mounting substrate of the present invention is preferably used is a millimeter wave band of several tens to several hundreds GHz band.

  The lower conductor plate and the upper conductor plate constituting the non-radiative dielectric line are made of metals such as copper, aluminum, iron, SUS (stainless steel), silver, gold, and platinum in terms of high electrical conductivity and workability. It is preferable to use a flat metal plate made of forging, casting, die casting, grinding, or the like. Or what formed the conductor layer which consists of these metals on the surface of the flat insulating board which consists of ceramics, resin, etc. may be used.

  The dielectric line is a line-shaped member made of a dielectric resin material such as ethylene tetrafluoride or polystyrene, or a dielectric inorganic material such as ceramics. As the material, resin materials such as ethylene tetrafluoride, polystyrene, and glass epoxy resin, or ceramics such as alumina ceramics, glass ceramics, and forsterite ceramics may be used depending on required characteristics.

  Then, using the diode mounting substrate of the present invention as described above and the diode mounted on the surface thereof, and the nonradiative dielectric line connected to the diode to form a millimeter wave circuit, the millimeter wave module of the present invention Is configured. As a result, it is possible to stably obtain desired diode characteristics as desired utilizing the features of the diode mounting substrate of the present invention, and to stably obtain desired characteristics as a millimeter wave module. Become.

  Next, a specific example of the diode mounting substrate of the present invention will be described.

  First, a low-temperature fired glass ceramic substrate with a relative dielectric constant of 4.7 is used, and a number of diode mounting pads and high-frequency choke patterns are formed on the surface in the pattern shown in FIG. 100 pieces of the diode mounting substrate A of the present invention were manufactured by cutting out into a rectangular shape having a size of.

  This glass ceramic substrate does not contain reinforcing materials such as fibers inside, and the relative dielectric constant is isotropic inside the substrate and there is no distribution in any direction, and a diode is mounted inside the substrate. It is uniform in a plane parallel to the surface.

  At this time, in order to cut out a large number of mounting substrates, in order to investigate the variation in diode characteristics due to the mounting substrate, 10 rows are arranged at a pitch of 8.19 mm on the side of the 8 mm side, For the side, 10 rows were arranged at a pitch of 3.9 mm, a large number of rows were formed in a vertical and horizontal arrangement, and 100 pieces were cut out individually.

  Further, as a comparative example, the same pattern as described above was formed using a glass epoxy substrate having the same relative dielectric constant of 4.7, cut into the same size, and 100 conventional diode mounting substrates B were similarly produced.

  In this glass epoxy substrate, a glass cloth made of glass fibers woven at a pitch of approximately 3.9 mm is laminated and embedded in an epoxy resin in parallel with the surface. Therefore, in this glass epoxy substrate, the relative dielectric constant changes with a period of 3.9 mm due to the glass fiber and the epoxy resin in the plane passing through the glass cloth layer.

  In this diode mounting substrate B, in order to change the positional relationship between the diode mounted on the surface and the glass fiber inside the substrate with minute variations, the side of 8 mm of the substrate is parallel to the direction of the glass fiber. Ten rows were arranged at an 8.19 mm pitch, 10 rows were arranged at 1.8 mm sides at a 3.9 mm pitch, a large number were formed in a vertical and horizontal arrangement, and 100 pieces were produced by cutting them individually.

  As a result, in the direction along the side of 8 mm, the length of 10 substrates corresponds to 21 pitches of the glass fiber, and the positional relationship between the diode and the glass fiber is periodic among these 10 substrates. Will change. Further, in the direction along the side of 1.8 mm, the positional relationship between the diode and the glass fiber is always the same.

  Then, a Schottky barrier diode is mounted on each of the diode mounting boards A and B, and this is attached to one end of the non-radiating dielectric line, and the other end of the non-radiating dielectric line is connected to the network analyzer. The frequency characteristics of the reflection coefficient were obtained for each of the case where a current of 1 mA was passed in the forward direction of the Schottky barrier diode and the case where a voltage of -2 V was applied in the reverse direction. Thereafter, the frequency at which the difference in reflection coefficient is the largest is defined as the switching frequency, and the switching frequency is obtained for each of the diode mounting boards A and B.

  The measurement results of the diode substrates A and B for 100 pieces obtained as described above are shown as diagrams in FIGS. 2 and 3, respectively. Here, the column on the horizontal axis indicates the position of the column arranged at the pitch of 8.19 mm, and the row in the plot and the characteristic curve indicates what of the rows arranged at the pitch of 3.9 mm. Indicates whether it was located on the line. The vertical axis indicates the switching frequency (unit: GHz).

  As is apparent from the results shown in FIG. 2, the variation in the characteristics of the Schottky barrier diode mounted on the diode mounting substrate A of the present invention using the low-temperature fired glass ceramic substrate is small, and the inter-row and inter-column The desired uniform characteristics are stably obtained. In this example, the reflection coefficient is entirely within the range of 0.15 GHz.

  On the other hand, in the result shown in FIG. 3, although the difference between the rows is small, the reflection coefficient fluctuates greatly between the columns with approximately 10 columns as one cycle. As a result, as described above, the positional relationship between the Schottky barrier diode and the glass fiber changes with 10 cycles as one cycle, and the relative permittivity changes in a plane parallel to the surface, as described above. As a result, the relative permittivity of the substrate changes with respect to the mounting position of the diode, whereas there is almost no change in the positional relationship between the rows and there is no difference in the relative permittivity.

  From these results, according to the diode mounting substrate A of the present invention, the relative permittivity is uniform in a plane parallel to the surface on which the diode is mounted inside the substrate, and there is no distribution of the relative permittivity. From this, it was confirmed that the diode to be mounted was a diode mounting substrate capable of stably obtaining good and uniform diode characteristics.

  Next, mount the Schottky barrier diode mounted on these diode mounting boards A and B on the switch circuit in the millimeter wave module composed of non-radiative dielectric lines, and investigate the variation in switching frequency. did.

  As a result, in the embodiment of the millimeter wave module of the present invention in which the diode mounting substrate A of the embodiment of the present invention is mounted in correspondence to the above result, the variation of the switching frequency for each diode mounting substrate A is 0.15 GHz. On the other hand, in the millimeter wave module of the comparative example on which the diode mounting board B of the comparative example was mounted, the variation was as large as 0.70 GHz.

  From this result, according to the millimeter wave module of the present invention, it was confirmed that the variation in characteristics in the millimeter wave circuit by the nonradiative dielectric line was reduced by providing the diode mounting substrate of the present invention.

  Note that the above are merely examples of the embodiments of the present invention, and the present invention is not limited to these embodiments, and various modifications and improvements may be added without departing from the scope of the present invention. . For example, a metal film is provided on a substrate 1 made of a resin such as a liquid crystal polymer by a method such as copper bonding or thin film formation, and this is etched to form a diode mounting pad 2 and a choke pattern 3 as a conductor pattern. In that case, the substrate 1 can be deformed to some extent, and the degree of freedom in design can be increased.

It is a top view which shows an example of embodiment of the board | substrate for diode mounting of this invention. It is a diagram which shows the measurement result of the switching characteristic in the Example of the board | substrate for diode mounting of this invention. It is a diagram which shows the measurement result of the switching characteristic in the comparative example using the conventional board | substrate for diode mounting.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... Pad for diode mounting 3 ... Choke pattern

Claims (2)

A diode mounting board on which a diode is mounted on the surface, which is used for a high-frequency circuit block using a non-radiative dielectric line, and the relative dielectric constant is uniform in a plane parallel to the inside surface. A substrate for mounting diodes. A millimeter-wave module comprising: a non-radiative dielectric line; the diode mounting substrate according to claim 1; and a diode mounted on the surface thereof.

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